Irrigated Agriculture and Wildlife Conservation: Conflict on a Global Scale

/ The demand for water to support irrigated agriculture has led to the demise of wetlands and their associated wildlife for decades. This thirst for water is so pervasive that many wetlands considered to be hemispheric reserves for waterbirds have been heavily affected; for example, the California and Nevada wetlands in North America, the Macquarie Marshes in Australia, and the Aral Sea in central Asia. These and other major wetlands have lost most of their historic supplies of water and some have also experienced serious impacts from contaminated subsurface irrigation drainage. Now mere shadows of what they once were in terms of biodiversity and wildlife production, many of the so-called "wetlands of international importance" are no longer the key conservation strongholds they were in the past. The conflict between irrigated agriculture and wildlife conservation has reached a critical point on a global scale. Not only has local wildlife suffered, including the extinction of highly insular species, but a ripple effect has impacted migratory birds worldwide. Human societies reliant on wetlands for their livelihoods are also bearing the cost. Ironically, most of the degradation of these key wetlands occurred during a period of time when public environmental awareness and scientific assertion of the need for wildlife conservation was at an all-time high. However, designation of certain wetlands as "reserves for wildlife" by international review boards has not slowed their continued degradation. To reverse this trend, land and water managers and policy makers must assess the true economic costs of wetland loss and, depending on the outcome of the assessment, use the information as a basis for establishing legally enforceable water rights that protect wetlands from agricultural development.     

Antecedents of injury among youth in agricultural settings: a longitudinal examination of safety consciousness,dangerous risk taking,and safety knowledge

PROBLEM: Injuries are the leading cause of death for adolescents in the United States. METHODS: This study longitudinally examined three psychological mediators of injury among 3,081 youths in agricultural settings: (a) safety consciousness, (b) dangerous risk taking, and (c) safety knowledge. These variables are examined within a nomological network of contextual variables. RESULTS: Cross-sectional results revealed that safety consciousness and dangerous risk taking were the strongest predictors of reported injury at Time 1 and Time 2. Safety knowledge had an unexpected negative association with injury, albeit weak. As predicted, participating in safety activities was positively associated with safety consciousness, and time spent working was strongly associated with safety knowledge. Furthermore, self-esteem had both positive and negative safety outcomes, suggesting a more complex functioning. Males exhibited fewer safety cognitions than females as predicted. Longitudinal data also revealed that injury at Time 1 and dangerous risk taking were the strongest predictors of Time 2 injury. IMPACT ON INDUSTRY: Results from this study emphasize the importance of assessing dangerous risk-taking perceptions when attempting to predict future injuries.     

The transtheoretical model of change in adolescents: implications for injury prevention

INTRODUCTION: Many injury prevention interventions require changes in human behavior to reduce self-risk or risk to others. Promising injury prevention interventions may be discarded if they lack power to create a significant difference in outcomes when judging their ability to "move a person from nonaction or negative action to positive action (safety)." The transtheoretical model of change (TMC) allows greater sensitivity in detecting along the change process where an intervention may be effective. The stages of change consist of precontemplation, contemplation, preparation, action, maintenance, and termination. Change is not viewed as an "all or none phenomenon." METHOD: Use of the TMC was examined using a quasiexperimental, cross-over design involving high school agriculture students enrolled in 21 schools in Kentucky (n=9), Iowa (n=7), and Mississippi (n=5). A series of physical and narrative simulations (safety training exercises) were developed with a focus on preventing amputation, spinal cord injury, hypersensitivity pneumonitis, and noise-induced hearing loss. Contemplation and action, as part of the TMC, were measured using a 10-item, Likert-type, stages of change (SOC) instrument comprised of two subscales (reliability coefficients were.88 and.81, respectively). The final sample consisted of 790 students (373 treatment and 417 control). RESULTS: There was a significant group effect for both contemplation, F(1,732)=197.4; p<.0001, and action, F(1,730)=106.1; p<.0001. A convenience sample of 29 of the participating students was selected for follow-up farm visits 1 year postparticipation. Of these students, 25 (86%) had made safety behavior changes in their farm work. IMPACT ON INDUSTRY: The use of the TMC model can provide researchers with greater precision in examining intervention effectiveness in promoting change.     

Preparation of agricultural residue anion exchangers and its nitrate maximum adsorption capacity

Anion exchangers were prepared from different agricultural residues (AR) after reaction with epichlorohydrin and dimethylamine in the presence of pyridine and N,N-dimethylformamide (EDM method). Agricultural residues anion exchangers (AR-AE) produced by the EDM method were inexpensive and showed almost the same NO₃⁻ removal capacities as Amberlite IRA-900. AR-AE produced from AR with higher hemicelluloses, lignin, ash and extractive contents resulted in the lower yields. Sugarcane bagasse with the highest -cellulose contents of 51.2% had the highest yield (225%) and lowest preparation cost. The highest maximum adsorption capacity (Q_max) for nitrate was obtained from rice hull (1.21 mmol g⁻¹) and pine bark natural exchangers (1.06 mmol g⁻¹). No correlation was found between Q_max and -cellulose content in the original AR. AR-AE produced from different AR demonstrated comparable Q_max due to the removal of non-active compounds such as extractives, lignin and hemicelluloses from AR during the preparation process. Similar preparation from pure cellulose and pure alkaline lignin demonstrated that the EDM method could not produce anion exchangers from pure lignin due to its solubilization after the reaction with epichlorohydrin.     

中国农业重旱区及其特征

中国的农业重旱省区与气象干旱区不相吻合,雨水较丰的湖南、湖北两省单位耕地面积的多年平均受旱程度亦很严重。解放以来我国一半以上受旱面积发生在河北、山西、山东、河南、安徽、湖北、湖南7省重旱区。     

Minimizing contamination hazards to waterbirds using agricultural drainage evaporation ponds

In much of the San Joaquin Valley, California, USA, inadequate drainage of applied irrigation water and accumulating salts in the soil have necessitated the installation of subsurface tile drainage systems to preserve crop productivity. At present, these subsurface drainage waters are disposed of by means of evaporation ponds or discharges into the San Joaquin River. Unfortunately, most of these agricultural drainage waters contain high concentrations of salts and naturally occurring trace elements, such as selenium, and recent evidence indicates that substantial numbers of waterbirds are exposed to contamination by selenium in the evaporation ponds. In order to avoid, minimize, or mitigate the adverse impacts on wildlife using the ponds, alternative pond management methods must be identified and evaluated for implementation. A number of methods have the potential to be cost-effective in significantly reducing the contamination hazard to birds using agricultural evaporation ponds. Twenty general methods were evaluated in this study, and four methods are recommended for implementation: remove levee vegetation, remove windbreaks, deepen the ponds, and haze birds. A number of other methods are recommended for further consideration because they appear to have good prospects for reducing the contamination hazard: steepen interior levee slopes, apply herbicides and insecticides, place netting on pond shorelines, and provide freshwater habitat adjacent to evaporation ponds. It may be necessary to use a combination of methods to effectively control selenium contamination of aquatic birds because it is unlikely that a single affordable pond management method will be able to entirely eliminate the contamination hazard.     

A regional environmental information system for analyzing and predicting the impacts of nonferrous mining on an agricultural environment

Mineral exploitation is a necessary component of China's economic development goals. Such exploitation brings with it the potential for serious environmental degradation. Careful environmental impact assessments of mining projects are required in order to implement China's environmental protection law and identify measures for protecting surrounding agricultural environments. This article describes an environmental information system that has been developed for the purpose of assisting with the environmental impact assessment of nonferrous mining operations with a particular focus on agricultural impacts. An application of the environmental information system to the Yongping copper mine, located in Jiangxi Province, is discussed. The role of the environmental information system is analyzing and predicting soil contamination from heavy metals and other types of impacts from this mining operation is described. The environmental information system is designed for implementation on an IBM PC/XT microcomputer. The experience gained from the Yongping copper mine application and the growing popularity of microcomputers in China indicate a significant potential for the effective use of a microcomputer-based environmental information system in other parts of China.     

Forests and competing land uses in Kenya

Indigenous forests in Kenya, as in other developing countries, are under heavy pressure from competing agricultural land uses and from unsustainable cutting. The problem in Kenya is compounded by high population growth rates and an agriculturally based economy, which, even with efforts to control birth rates and industrialize, will persist into the next century. Both ecological and economic consequences of these pressures need to be considered in land-use decision making for land and forest management to be effective. This paper presents one way to combine ecological and economic considerations. The status of principal forest areas in Kenya is summarized and competing land uses compared on the basis of ecological functions and economic analysis. Replacement uses do not match the ecological functions of forest, although established stands of tree crops (forest plantations, fuel wood, tea) can have roughly comparable effects on soil and water resources. Indigenous forests have high, although difficult to estimate, economic benefits from tourism and protection of downstream agricultural productivity. Economic returns from competing land uses range widely, with tea having the highest and fuel wood plantations having returns comparable to some annual crops and dairying. Consideration of ecological and economic factors together suggests some trade-offs for improving land allocation decisions and several management opportunities for increasing benefits or reducing costs from particular land uses. The evaluation also suggests a general strategy for forest land management in Kenya.The views and interpretations expressed in this article are those of the authors and should not be attributed to the World Bank, its affiliated organizations, or any individual acting on their behalf.     

USING CROP YIELD AND EVAPOTRANSPIRATION RELATIONS FOR REGIONAL WATER REQUIREMENT ESTIMATION1

ABSTRACT: Values of dry biomass of corn, sugarcane, sorghum, rice, taro, millet, cotton, cowpeas, soybeans, and velvet beans as related to the evapotranspiration (ET) were studied. The linear regression model was sufficiently accurate to establish the crop dry biomass and ET relations. A water-use efficiency index (WUE), which is defined as the additional crop dry biomass per unit ET, is used in this study. The WUE were grouped into high, medium, and low categories. The WUE varied from greater than 35 kg ha^-1/mm for the high category, between 15 and 35 kg ha^-1/mm for the medium category, and less than 15 kg ha^-1/mm for the low category. Application of the established model to the Everglades Agricultural Area, Florida, showed that the regional El can be predicted from the known regional crop yields. The crop yield and ET relations could be used as a potential tool to improve water resources planning and management practices for crop production.     

WATER SUPPLY,TREATMENT, DISTRUBTION,AND REUSE OPTIMIZATION IN ARID URBAN AREAS1

ABSTRACT: A Management level model has been formulated in which a system analysis format is employed to answer some of the basic questions regarding urban water management strategies The model incorporates a multilevel optimization scheme to coordinate urban water supply, distribution, and wastewater management. A test of the model's utility is made in an application to the water management problems of the Denver, Colorado metropolitan area. Denver has utilized both agricultural transfers and transmountain diversions to supplement the natural stream resources of the South Platte River. Although plans are being made to increase the capacity of these sources, increasingly stringent standards on the area's effluents are enhancing the feasibility of reclaiming and recycling a portion of the wastewater. The urban model used in this study indicates the decision points at which respective strategies are introduced. However, by formulating the model from a planner's viewpoint, the most important results gained from the analysis are the costs of various institutional constraints which may restrict the decision maker's ability to implement optimal policies.